1. Field of the Invention
The present invention pertains to dyes and methods of use thereof. Even more particularly, the present invention pertains to means and methods for dyeing fabric. Even more particularly, the present invention pertains to water-soluble titanium salt-tannin dyes and the use thereof in dyeing fabric.
2. Prior Art
As is known to those skilled in the art, natural dyes provide hues and tones to textiles which are not attainable with synthetic dyes. Thus, where natural dyes, such as vegetables dyes, can be employed, it would be most advantageous for the garment manufacturer.
While vegetable dyes may take on the fiber without any other chemicals, it, like most dyes, usually requires another chemical or catalyst to join the chemical to the fiber. This catalyst is defined in the art as a "mordant". Mordants are applied across the spectrum of textile dyeing including natural fiber and synthetic fiber dyeing. Thus wool, cotton, silk, polyester, leather, etc. are all subject to a dyeing process which requires the use of mordants. Furthermore, mordants are employed whether using natural or synthetic dyes. A mordant may either brighten or dull the hue, depending on the selection thereof. Also, a mordant be may be either water-soluble or insoluble.
Typically, in dyeing natural fibers such as wool and cotton, the mordants which are employed are alum, chrome, and tin when seeking brightening mordants. For dulling, the mordants typically employed are copper and iron.
While all fibers and fabrics are subjected to dyeing processes, one of the fastest growing markets for dyed fabric and which has enjoyed continual growth over the last few years, is the denim fabric market. Denim blue jeans, jackets, etc. are an integral part of any wardrobe. Not only are there "worker" denim fabrics but "designer" fabrics and apparel as well. With this ever growing market, there is a need to produce such dyed fabric as quickly, economically and as efficiently as possible.
To accelerate the production of denim fabric, there has recently been developed the "quick wash" denim fabric which can be washed down to produce all of the various shade depths and appearances of denim currently in demand. Quick wash denim is described in the May, 1994 issue of American Dye Stuff Reporter at pages 15-16. Generally, denim being a cotton fabric it is difficult to dye with natural dyestuffs. Yet, and as is known to those skilled in the art to which the present invention pertains, indigo dye is employed to impart the blue hue to the denim fabric. Green hues may be obtained by dyeing the fabric in an indigo vat and then overdyeing with a yellow-producing dye. However, other colors are difficult to achieve.
Thus, it is to be appreciated that the use of naturally occurring dyes, other than indigo, to enhance the dyeing properties, such as laundry washed fastness and color tinctorial value would necessarily enhance denim jean marketability. Moreover, if such dyes could be applied to other fabrics using water-soluble mordants apparent advantages occur.
The use of tannins, which are vegetable dyes, as fabric or fiber dyes and as tanning agents for leathers is, of course, well known. Likewise, the use of tannins as mordants for other dyes has been known. Also, the use of other mordants to bind tannins is known. For example, the use of titanium potassium compounds as fixing agents for dyes has been known in the prior art. See, inter alia, U.S. Pat. No. 3,699,137. However, the use of water-soluble titanium salts in combination with tannin dyes as a mordant has not heretofore been known. In this regard, the use of basic colors or dyes on tannin-mordanted cotton is well documented. Typically, the cotton is mordanted with the tannin and either an antimony salt, e.g. tartar emetic, or an aluminum salt, e.g. aluminum potassium sulfate hydrate crystals. Moreover, the use of basic dyes after pre-treatment of the cotton with a stain resistant agent has been accomplished. The phenolic group of the stain resistant agent bonds to the cellulose of the cotton leaving the sulfonic group of the stain resistant agent free to bind the basic dye.
Similarly, basic dyes have been used to color not only cotton, but anionic fibers, wool and silk, as well as blends of cotton with synthetic fibers since basic dyes have a strong affinity for such. However, the use of water-soluble titanium based salts in combination with tannin dyes as mordants for basic dyes has not been taught heretofore.
It has been found that the use of titanium salts in combination with tannin substances enables the dyeing on both natural as well as synthetic fibers, as well as enabling overdyeing to provide deeper hues.
As will subsequently be detailed, the present invention provides water-soluble titanium salt-tannin dyes for use in both dyeing of textiles and as a mordant for natural and synthetic fibers. Such an aqueous dye is pre-eminently useful in accelerating and enhancing the dyeing of denim fabric as well as enabling the dyeing of cotton with basic colors.